Parasitism of Pickleworm and Melonworm (Lepidoptera: Pyralidae) by Cardiochiles diaphaniae (Hymenoptera: Braconidae)

Abstract

Pickleworm, Diaphania nitidalis (Stoll), and melonworm, Diaphania hyalinata (L.), larvae were susceptible to parasitism by Cardiochiles diaphaniae Marsh. Melonworm larvae were more susceptible to parasitism than pickleworm, but both exhibited reduced weight gain and head capsule growth in later stadia compared with nonparasitized conspecifics and then perished following initiation of wandering before pupal molt. Melonworm larvae parasitized when in advanced stadia achieved a greater final weight than larvae parasitized when young. Parasitoid larval development time was longest following parasitization of young melonworm, but not significantly different in melonworm larvae parasitized in middle or later instars. Compared with nonparasitized melonworm larvae, the prepupal wandering stage was abbreviated in melonworm larvae parasitized when young, and extended in melonworm larvae parasitized in later instars. Overall, parasitoid development time was significantly longer in pickleworm hosts than melonworm. Adult parasitoid weight increased with host age at the time of parasitization when melonworm served as host and was highest in middle-instar larvae when pickle worm served as host. C. diaphaniae developing in pickleworm larvae weighed significantly more than those developing in melonworm larvae.